This invention relates generally to gas lasers, and, more particularly to a waveguide CO.sub.2 laser which is compact, lightweight and produces a high power output.
Since the development of the first working lasers, considerable time and effort has been expended in the search for lightweight, compact high output laser systems. The possible applications of such high power lasers are unlimited in the fields of communication, manufacturing and medicine. In particular in the fields of medicine and communication it is of utmost importance that the laser be lightweight and still produce high output. To date, the gas laser, and in particular, the CO.sub.2 laser has been largely used in these fields.
Gas laser operation requires that a population inversion be established between upper energy levels and lower energy levels of the lasing medium. In the CO.sub.2 laser (generally an electrically excited mixture of carbon dioxide, nitrogen and helium) laser operation may be achieved by the resonant transfer of energy, through collisions from a first gaseous substance, designated the "energizing substance" such as vibrationally excited molecular nitrogen (N.sub.2), to a second substance designated the "lasing substance" such as carbon dioxide (CO.sub.2). Nitrogen and CO.sub.2 may be fully mixed together, such as in a fully mixed gaseous plasma, while the substances in this mixture are raised to respective specific energy levels, favorable to laser emission as a result of the electron collisions in an electronic plasma.
During this procedure it is necessary that the nitrogen have sufficient energy in its vibrational mode so as to impart a substantial amount of energy to CO.sub.2 in the 001 state, which is commonly referred to as the upper laser level for CO.sub.2 molecules. The very efficient energy transfer between the nitrogen and the carbon dioxide results from a near identity of the energy spacing of certain of the vibrational states of these two substances.
Thus, in the present state of the gas laser art, lasing (which is the coherent stimulated emission of quanta of light energy) of one substance results from that substance being brought to a high, nonequilibrium energy state as a result of collisions with an energizing gas excited to a vibrational energy level which closely matches an energy level of the lasing substance (i.e., the upper lasing level in CO.sub.2). Simply stated, at least one CO.sub.2 molecule which is present in a region of population inversion will spontaneously emit a photon with an energy equal to the difference between the upper laser energy level and the lower laser energy level for a CO.sub.2 molecule. This is a quantum of light energy which is reflected back and forth in the resonant cavity. The photon will impinge on another CO.sub.2 molecule and cause a rapid, stimulated emission of a second photon. This photon is also reflected back and forth in the resonant cavity, which brings about a continuing avalanche of stimulated photon emission, at the lasing wavelength. This sequence will occur nearly instantaneously so that lasing is established in say, nanoseconds. The useful laser output is derived by coupling light energy out of the oscillating and/or amplifying resonant cavity.
Within the gas laser the population inversion is achieved by "pumping" the higher energy vibrational states in the media through the action of an electric current (electric discharge).
Unfortunately, even though the gas laser produces a high output, there are many problems relating to its use, in particular, the laser itself fails to be as compact and lightweight as required. Since it is essential within satellites that a laser utilized for communications does not add to the overall weight of the satellite, much research in this field is still underway. Futhermore, in the field of medicine which requires hand-held, portable laser devices that are capable of providing precision and "bloodless" cutting, the basic gas laser still leaves much to be desired.